/*
 * All content copyright Terracotta, Inc., unless otherwise indicated. All rights reserved.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not 
 * use this file except in compliance with the License. You may obtain a copy 
 * of the License at 
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0 
 *   
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 
 * License for the specific language governing permissions and limitations 
 * under the License.
 * 
 */
package org.go.matchers;

import org.go.util.Key;

/**
 * Matches using an NOT operator on another Matcher. 
 *  
 * @author jhouse
 */
public class NotMatcher<T extends Key> implements Matcher<T> {
	/**
	 * 
	 */
	private static final long serialVersionUID = -8473213221391664494L;

	/**
	 * Create a NotMatcher that reverses the result of the given matcher.
	 */
	public static <U extends Key> NotMatcher<U> not(Matcher<U> operand) {
		return new NotMatcher<U>(operand);
	}

	protected Matcher<T> operand;

	protected NotMatcher(Matcher<T> operand) {
		if (operand == null)
			throw new IllegalArgumentException("Non-null operand required!");

		this.operand = operand;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		NotMatcher other = (NotMatcher) obj;
		if (operand == null) {
			if (other.operand != null)
				return false;
		} else if (!operand.equals(other.operand))
			return false;
		return true;
	}

	public Matcher<T> getOperand() {
		return operand;
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + ((operand == null) ? 0 : operand.hashCode());
		return result;
	}

	@Override
	public boolean isMatch(T key) {
		return !operand.isMatch(key);
	}
}
